Cancer is an uncontrolled growth of abnormal cells on or within the body of humans and animals. Cancer may be benign or malignant, and malignancies may be localized or may invade adjacent tissue and spread throughout the body of the subject. There are many types of malignant cancer including lung cancer, blood cancer, brain cancer, perianal gland adenoma, squamous cell carcinoma, and the like. The incidence of cancer in companion animals, such as, for example dogs, cats and the like is increasing, and cancer is now considered to be the leading cause of death in older animals. It is believed that the annual incidence rate for cancer in dogs is about 2 to 2.5% (about the same as humans) and about 1.5 to 2% for cats.
Several studies suggest that the cancer having the highest incidence in animals (e.g., companion animals, reptiles, and birds) are mast cell tumor (16.8%), lipoma (8.5%), histiocytoma (8.4%), perianal gland adenoma (7.8%), sebaceous gland hyperplasia adenoma (6.5%), and squamous cell carcinoma (6.0%), among others. Some of the aforementioned cancers are benign and some are malignant. Unfortunately, benign tumors can be as dangerous as malignant growths if they are allowed to grow to a point where they prevent normal bodily function. Additionally, benign tumors have the potential to become malignant through a process known as tumor progression.
Generally, veterinary oncologists have “off-label” drug use privileges. Off-label drug use means that the veterinary oncologists can use drugs approved for one species (including humans) freely in another species. Currently, veterinary oncologists tend to select chemotherapeutics exhibiting significant positive results in human oncology for treating cancer in animals.
Chemotherapeutic agents are typically systemically delivered and may reduce tumor bulk and delay metastasis, but there is a profound morbidity associated with this type of treatment. Despite the many disadvantages and side effects of employing these strongly cytotoxic drugs, chemotherapeutic agents have found extensive use due to the positive anti-carcinogenic results experienced. Because of the side effects associated with the systemic delivery of chemotherapeutic agents, there is a substantial interest in delivering chemotherapeutic agents in a manner which directs their activity toward the abnormal cells. This activity toward the abnormal cells would avoid the exposure of sensitive normal cells to the cytotoxic effects of the drugs, both in the vicinity of and distant from the abnormal cell growth.
Localized chemotherapy treatments (e.g., intralesional injections) direct the anti-cancer drugs into the part of the body where the cancer is located, thereby allowing higher concentration of the drugs at the administration site and further minimizing the side effects in patients. However, side effects still occur since the drugs can be absorbed into the bloodstream and travel throughout the body due to the inability of current injection preparations to remain at the site of contact and only target the cancer cells. Some drawbacks associated with chemotherapy treatments include: limited use at certain stages of the disease; chemotherapeutic drugs cannot distinguish between malignant cancer cells and normal cells; and toxicity to normal, healthy, rapidly growing or self-renewing tissues within the body.
Therefore, there is a need for a pharmaceutical composition including chemotherapeutic agents that are non-systemically delivered and do not possess the limitations listed immediately above.